多索-梁结构固有振动特性分析

NATURAL VIBRATION ANALYSIS OF MULTI-CABLES-STAYED BEAM STRUCTURES

进行了单索-梁结构和二索-梁结构模型固有振动试验,采用斜拉桥整体动力分析有限元方法建立了索梁结构有限元模型,与试验结果进行的比较验证了所建有限元模型的正确性。通过对单索-梁结构至四索-梁结构的固有振动特性的有限元分析表明,斜拉索的存在和数量对索梁结构的面内固有频率影响较大,对面外固有频率影响很小;斜拉索的增加使索梁结构面内振动频率增大的主要原因是斜拉索对主梁起到竖向支承的作用。将斜拉索竖向支承作用简化为弹性支撑,考虑斜拉索水平分力对主梁轴力的影响,推导得到了多索-梁结构面内固有振动的频率方程和振型函数,与有限元计算结果进行的对比说明了所得简化公式的正确性和适用性。

Natural vibration tests of single-cable-stayed beam and double-cables-stayed beam are conducted. Models of the two structures are established by the finite element method for the global dynamic analysis of cable-stayed bridges, and their accuracy is verified by the test results. According to the finite element analysis of single-cable-stayed beams to four-cables-stayed beams, the influence of the existence and number of cables on in-plane natural frequency is large, but that on out-of-plane natural frequency is small. Because cables support the beam vertically, the increase in the number of cables will lead to an increase in the in-plane natural frequency of cable-stayed beam structures. By assuming the cable＇s vertical support to be elastic and considering the effect of the horizontal component of cable force on the axial force of the beam, the frequency equation and mode function of in-plane natural vibration for multi-cables-stayed beams are derived. The validity and applicability of the simplified formulas are verified by finite element analyses.